1. Field of the Invention
The present invention relates generally to clamping members for attachment to a jaw-type surgical clamping device for atraumatically occluding a vessel or other tubular structure. More particularly, the invention relates to clamping members that include opposable resilient pads having surface protrusions where the protrusions of the opposing pads interdigitate to provide improved gripping of the occluded vessel or tubular structure.
2. Description of the Related Art
Instruments for occluding blood vessels or other tubular structures of a patient""s body during surgery, such as conventional metal or rigid surgical clamps or clips, are well known. Such instruments, however, are known to cause trauma to the clamped vessel at the clamping site. A number of atraumatic instruments have been developed for reducing or eliminating the trauma to a vessel during occlusion of the vessel. U.S. Pat. No. 3,993,076 to Fogarty, et al. discloses a device whereby a vessel is occluded by using a resilient tape to press a vessel against a resilient pad. However, this device suffers from the disadvantage that it slips easily. For example, the pulsations of an occluded artery can tend to force the device off of its clamped position on the occluded artery. Conventional surgical clamps have also been adapted to include jaw surfaces containing resilient members or pads. These devices likewise are prone to slipping off of the clamped vessel. This can be especially problematic in situations where, due to obstructions, a vessel has been clamped with only the distal tips of the clamp jaws. In such situations, the vessel can be especially prone to slipping in the direction of the distal tips.
Other attempts have been made to atraumatically occlude a vessel in a more secure fashion. U.S. Pat. No. 3,746,002 to Haller discloses a vascular clamp with resilient gripping members located on the jaws. A plurality of pin members are embedded within the gripping members, the pin members being of a length such that when a vessel is clamped between the members, the resilient material deflects to accommodate the vessel, exposing the pin members which grippingly engage the outer layer of the vessel, thus securing the vessel to the gripping member. While the Haller device is less traumatic to a vessel than other occlusion devices, it nevertheless has the disadvantage of traumatizing the outer layer of the vessel.
U.S. Pat. No. 4,821,719 to Fogarty discloses a vascular clamp device containing resilient pads with Velcro-like hooks. The hooks interact with the external adventitial layer of the vessel forming a cohesive-adhesive relationship with the vessel similar to the bonding of Velcro materials. While this device offers a less traumatic way to occlude a vessel, the cohesive-adhesive nature of the bond can result in the removal of some of the adventitial layer of the vessel when disengaging the device.
U.S. Pat. No. 3,515,139 to Mallina discloses surgical forceps with hard plastic inserts having spherical protuberances and complementary grooves or spherical cavities. U.S. Pat. No. 3,503,397 to Fogarty discloses surgical clamps with jaw inserts having hard plastic teeth along the edges of the insert with a softer component along the interior of the insert. The hard teeth of this device serve to resist movement of a clamped vessel laterally of the jaw, but do so at increased risk of trauma to the vessel.
There is thus a need for a surgical clamp which atraumatically occludes vessels with improved gripping capabilities while simultaneously avoiding the disadvantages previously associated with existing surgical clamps or occlusion devices.
The present invention provides for opposing surgical clamp members having opposing resilient pads with clamping surfaces that have interdigitating protrusions or xe2x80x9cteethxe2x80x9d that extend from the surfaces of the pads for engagement with a vessel. As used herein, the general term xe2x80x9cvesselxe2x80x9d shall refer to a blood vessel or other tubular body structure. The protrusions are arranged in rows lengthwise along pairs of opposable pads such that when the pads are brought together, the protrusions of one pad interdigitate with the protrusions of the other pad. When engaged with a vessel, portions of the vessel, including the adventitial layer, will be forced into the interdigital spaces between the protrusions, providing for improved gripping of the vessel or tissue. At the same time, the resiliency of the protrusions ensures against trauma to the clamped vessel or tissue.
The protrusions themselves can be of varying shapes, including cylindrical-shaped protrusions or wedge-shaped protrusions. Where cylindrical protrusions are used, the protrusions can culminate in varying tip shapes, for example, blunt cut, hemispherical or conical tips can be used. The protrusions can also include discrete gripping edges to further increase the traction on an engaged vessel. In every case, the resiliency of the protrusions is such that the protrusions will deflect upon engagement with a vessel but will not distort too greatly from their overall original shape. It is important that the resiliency of the pad as a whole is adequate to impart a cushioning effect upon the clamped vessel, while at the same time the protrusions of the pad retain enough of their original shape to effectively interdigitate with the protrusions of the opposing pad when the pads are brought together in engagement with the vessel. In this manner, the engaged vessel is effectively gripped while minimizing trauma or damage to the vessel. Optimally, the pad itself is of a single-piece construction with the protrusions integrally formed with the remainder of the pad.
In an embodiment of the invention, the relative resiliency of the pad can be altered by including a series of through holes located below the pad surface and transverse to the length of the pad. The holes can be of varying diameter and varying spacing. One skilled in the art will realize that multiple arrangements of through holes can be used, provided that the result is that the underlying portion of the pad containing the through holes is more easily deflected than the protrusions of the overlying surface portion of the pad. The pad thus provides a greater overall cushioning effect for a clamped vessel while at the same time providing the gripping protrusions with a sufficient hardness to resist excessive deformation upon engagement with a clamped vessel. The through holes can extend along the entire length of the pad or, alternatively, extend only along the portions of pad length, for example, along the center portion of the pad. In this latter configuration, the pad will be more easily deflected along the center portion and stiffer towards the ends of the pad. Vessels clamped in the center of the pads will be restrained from slipping toward the ends of the pads because movement of the vessel in those directions will be resisted in part due to the stiffer resilience of the end portions of the pads.
In further embodiments of the invention, the protrusions can be oriented to further resist movement of clamped vessel in particular directions relative to the pads. In one embodiment, the protrusions can be formed in the shape of wedges oriented perpendicular to the length of the pad with the raised ends of the wedges flush with the sides of the pad. In this configuration, movement of a clamped vessel in a direction transverse to the pad will be restricted by the raised ends of the wedges. By arranging the wedges in alternating fashion along the pad length, lateral or transverse movement of a clamped vessel relative to the pad is restricted. In other embodiments, the protrusions can be cylindrical and extend upward from the pad surface. In such configurations, lateral or transverse movement of the clamped vessel relative to the pad will be restricted in like fashion.